If you can accurately determine the positions of people and vehicles in large indoor spaces such as factories and warehouses, work efficiency and safety will improve dramatically. Demand for high-precision indoor positioning is rising, but traditionally it required complex equipment and specialized skills, making implementation difficult. Enter the next-generation device “LRTK,” which enables centimeter-level positioning simply by attaching it to a smartphone. This article explains the importance and challenges of indoor positioning in factories and warehouses, a simple method for high-precision positioning using LRTK and a smartphone, and applications ranging from point cloud data acquisition to DX (digital transformation).

The contents of this article will be useful to a wide range of readers, from on-site workers, factory managers, and DX leads to surveying professionals.

Table of contents

• The need for cm-level indoor positioning in factories and warehouses

• Challenges of indoor positioning and conventional technologies

• Easy centimeter-level positioning with a smartphone + LRTK

• Use cases expanding in factories and warehouses

• Acquisition of high-precision point cloud data and digital utilization

• Contribution to on-site DX and operational efficiency

• Summary: LRTK makes centimeter-level positioning easy in factories and warehouses

• FAQ

The need for cm-level indoor positioning in factories and warehouses

In production factories and logistics warehouses, it is ideal to accurately know the positions of workers, forklifts, equipment, inventory, and other items. For example, real-time tracking of a forklift’s current position can help reduce collision risks and optimize travel routes. Accurate position information can also drastically shorten the time spent searching for materials in a large warehouse. In this way, improving indoor positioning accuracy brings a wide range of benefits, from safety management to operational efficiency. The key is technology that can achieve GPS-like centimeter-level accuracy indoors.

Traditionally, achieving positioning accuracy on the order of a few centimeters indoors has been very difficult. General GPS signals are blocked by roofs and ceilings and do not reach indoors, and a smartphone’s normal location services typically have errors of several meters. On-site, people have relied on analog methods like floor markings or painstaking measurements with laser distance meters. However, those approaches cannot meet the requirements of DX—such as tracking people and objects in real time and accumulating data for analysis. What was needed was an easy-to-use, high-precision indoor positioning tool for the field.

Challenges of indoor positioning and conventional technologies

The difficulty of high-precision indoor positioning mainly stems from the fact that radio signals from GNSS satellites do not reach inside buildings. In open outdoor spaces with a clear view, RTK-GNSS can provide centimeter-level positioning, but the same method cannot be used inside structures. Consequently, various indoor positioning technologies have been developed and adopted.

Representative methods include the following:

• UWB (ultra-wideband) positioning: A technology that measures distance using radio pulses on the order of nanoseconds. If dedicated anchors (base stations) and tags are installed, positions can be identified indoors with errors of less than a few tens of centimeters. Adoption for asset management in factories and warehouses is progressing, and it is used in applications such as tracking moving forklifts with roughly 30 cm (11.8 in) accuracy. However, it requires installing multiple anchors as infrastructure, which incurs system construction costs.

• Self-positioning using IMU (inertial measurement unit): This method uses an IMU composed of accelerometers and gyros to integrate motion and estimate relative position. It does not require external radio signals and can continuously track position even where GNSS is unavailable. It can maintain high accuracy for short periods, but errors accumulate over time (drift), so periodic position corrections are essential.

• Positioning using SLAM: SLAM (Simultaneous Localization and Mapping) estimates one’s position while scanning the surrounding environment with a camera or LiDAR. Because it builds a map while determining the current location, it is widely used for robots that move autonomously indoors and outdoors. However, achieving accuracy in absolute coordinates requires additional measures; if started without a known reference, the entire map can be offset.

• GNSS repeaters: Devices that amplify and retransmit satellite signals received outdoors so that pseudo-GNSS signals reach inside buildings. They are used in practice as “tunnel GPS” in large tunnels, but unless implemented as an advanced system with multiple repeaters, it is difficult to cover an entire building interior and obtain accurate positions, making general adoption in factories and warehouses challenging.

As described above, it is difficult for a single technology to achieve cm-level indoor positioning by itself, and the current practice is to combine multiple methods depending on the use case. For example, a logistics warehouse might use UWB for real-time tracking of goods and vehicles while performing spot checks with laser measurements. Even so, the inability to easily achieve high-precision positioning as outdoors remained a bottleneck.

Easy centimeter-level positioning with a smartphone + LRTK

Against this backdrop, LRTK is a revolutionary device that enables centimeter-level positioning simply by “attaching it to a smartphone.” LRTK is a compact positioning unit that integrates a high-precision RTK-GNSS receiver and is used in combination with an existing smartphone. Until now, centimeter-level positioning required specialized GNSS surveying instruments or base stations, but with LRTK, you can collect positioning data seamlessly from outdoors to indoors using only a smartphone.

A smartphone alone typically has positioning errors of several meters, but attaching an LRTK can reduce that to a few centimeters. The secret is RTK (Real-Time Kinematic) technology. RTK uses correction information from a base station to cancel GNSS errors, and LRTK supports Japan’s quasi-zenith satellite system “Michibiki” and its centimeter-class augmentation service (CLAS). This enables stable centimeter-level positioning even at outdoor sites outside typical communication coverage.

How does LRTK help inside buildings? In fact, the combination of LRTK and a smartphone enables high-precision positioning that spans indoors and outdoors. One approach is to obtain a highly accurate reference position with LRTK outdoors somewhere on the factory premises, then enter the building and switch to relative positioning using the smartphone’s built-in IMU. By bringing the centimeter-accurate absolute coordinates obtained outdoors as an initial reference, high accuracy can be maintained for short periods during indoor movement. Another approach is that if a warehouse already has its own positioning system such as UWB anchors, you can pre-calibrate those coordinate systems with LRTK so continuous positioning with unified coordinates across indoor and outdoor areas becomes possible. In other words, LRTK bridges outdoor GNSS and indoor positioning technologies to support uninterrupted centimeter-level positioning.

Additionally, LRTK works seamlessly with a smartphone, making it extremely easy to use. Heavy tripods and cable connections are unnecessary—just attach a pocket-sized device to your smartphone and you’re ready. A dedicated app on the smartphone allows you to check your current position and positioning accuracy on the screen, and measurement data can be automatically saved and shared in the cloud. No special training is required; on-site staff familiar with everyday smartphone use will find it intuitive. The ease of smartphone integration means LRTK is a high-precision positioning tool usable not only by specialists but by anyone on site.

Use cases expanding in factories and warehouses

By leveraging LRTK, new efficiencies and DX can be realized across various scenarios in factories and warehouses. Here are some concrete examples.

• Layout measurement and equipment placement: You can measure the dimensions of a large factory floor and the placement of equipment simply by walking around with an LRTK-equipped smartphone. The acquired data can be used to create accurate floor plans and 3D models to support layout change planning. Tasks that previously required multiple people using tapes or laser distance meters can be completed in a short time.

• Inventory management and logistics optimization: If the positions of pallets and shelves are known to centimeter accuracy, picking and inventory operations become far more efficient. If carts or forklifts equipped with a smartphone and LRTK record the locations of inventory as they move, you can visualize in real time where items are located. Being able to check the current locations of goods and vehicles on an indoor map reduces wasted time searching and helps optimize logistic routes.

• Safety management and work support: High-precision position information contributes to safety measures. Systems that virtually zone hazardous areas and display alerts on a worker’s smartphone when they approach can be implemented more easily with LRTK. Combined with AR (augmented reality), you can display virtual lines on the floor to indicate walkways or show picking instructions on shelves with AR markers. Stable AR displays without positional drift can aid on-site training and error prevention.

Thus, centimeter-level indoor positioning with LRTK goes beyond merely knowing current locations and can revolutionize many on-site operations in factories and warehouses. When on-site staff and managers can share accurate position data, secondary benefits such as reduced communication loss and faster decision-making can also be expected.

Acquisition of high-precision point cloud data and digital utilization

Another strength of LRTK is the ability to obtain high-precision point cloud data in conjunction with a smartphone’s camera or LiDAR sensor. By scanning the surroundings with the smartphone’s LiDAR or camera while using LRTK positioning to give each point absolute coordinates, you can create precise 3D point clouds.

For example, if you walk through a warehouse aisle scanning shelves and pathways, you can quickly obtain a detailed 3D model that includes walls, equipment shapes, and piles of inventory. Traditionally, point cloud surveys with laser scanners were expensive tasks outsourced to specialists, but with LRTK, in-house staff can perform measurements as part of their routine work. The resulting point cloud data can be used as a digital twin of the entire building. Overlaying it with building drawings lets you verify whether actual shelf placements match the plan, check floor tilts or deformations, and support maintenance and improvement activities.

Sharing point cloud data in the cloud allows remote stakeholders to view the site three-dimensionally. You can hold pre-expansion meetings for factory equipment while checking the current layout in 3D, or estimate warehouse inventory volumes from point clouds to plan replenishment—enabling data-driven decision-making. LRTK makes advanced 3D data utilization, once accessible only to a few experts, within reach for many users.

Contribution to on-site DX and operational efficiency

Centimeter-level indoor positioning and point cloud data utilization directly drive on-site DX. Site management that used to rely on individual workers can become data-driven, and visibility and efficiency of operations will advance rapidly. Below are the benefits of introducing LRTK organized by stakeholder.

• On-site workers: Workers can confirm their position and target points on a smartphone, enabling them to start tasks without getting lost even in large facilities. Without surveying expertise, they can measure dimensions or record positions themselves, eliminating the need to call a surveying company for small measurements.

• Factory managers: Managers can accurately grasp production line and inventory layouts, providing more input for decisions on layout changes and equipment relocation. Real-time position information can be used for management tasks such as monitoring safety zones and controlling traffic flow to optimize the site.

• DX leads: Positioning and point cloud data from the field can be integrated and used in digital twins and IoT platforms. Centralizing indoor and outdoor data enables visualization of factory-wide activity and supports system development to improve productivity.

• Surveying professionals: Even in situations where indoor surveying was previously challenging, LRTK enables fast establishment of control points and as-built measurements. Without needing large tripods or laser scanners, surveying and inspection work becomes less burdensome and more efficient.

In this way, high-precision positioning with LRTK benefits multiple professions and supports a work-style transformation across the site. Because it leverages existing smartphones, introduction and operation costs can be relatively low and allow a small-start approach—making pilot deployments and phased rollouts easy.

Summary: LRTK makes centimeter-level positioning easy in factories and warehouses

Delivering centimeter-level accuracy for indoor positioning in factories and warehouses is no longer a dream. The arrival of the small device LRTK, which mounts on a smartphone, has dramatically simplified and advanced on-site positioning and management. Positioning that used to be handled only by specialists can now be done “by anyone, immediately, anywhere,” enabling accurate measurements throughout large facilities by in-house teams.

Knowing positions to centimeter accuracy becomes a trump card for on-site improvements—strengthening safety management, optimizing logistics, and refining layout. With smartphone integration enabling data sharing and point cloud measurement, LRTK is more than just a positioning device; it is a key solution for on-site DX. Use LRTK to overturn conventional thinking about indoor positioning and take the first step toward smarter factories and warehouses.

FAQ

Q: Can you really achieve centimeter-level positioning indoors? A: Maintaining centimeter-level accuracy using only GNSS for long periods in a completely enclosed indoor space is difficult, but LRTK makes this possible by operating seamlessly across indoor and outdoor areas. For example, you can obtain a highly accurate initial position outdoors and continue short-duration high-accuracy positioning indoors by combining IMU and other positioning technologies. Depending on the environment, you may also receive satellite augmentation signals near windows inside buildings and maintain a certain level of high accuracy.

Q: What is required to introduce LRTK into a factory or warehouse? A: Essentially, you can get started with an LRTK device and a compatible smartphone. Install the dedicated app on the smartphone, attach the LRTK and perform an initial positioning in a location with a view of the sky; after that you can make use of positioning data indoors. Existing infrastructure such as Wi‑Fi or UWB can be used in combination to improve accuracy and coverage.

Q: Do you need special skills to acquire point cloud data? A: No. Point cloud scanning using a smartphone camera or LiDAR is simple—just follow the app’s instructions. The acquired data is automatically aligned with position information, so it can be handled without needing specialized processing knowledge. Of course, advanced analysis benefits from expertise, but basic recording tasks can be carried out by anyone.

Q: The device connects to a smartphone—what about communications and power? A: LRTK incorporates a battery and a high-performance antenna and pairs with smartphones wirelessly (some models may use Bluetooth or dedicated connectors). It is designed for long operation on a single charge, reducing the risk of sudden power loss on site. For communications, positioning data can be uploaded to the cloud via the smartphone, and in places without network coverage LRTK can still receive satellite correction information on its own, providing reliability.

Q: How much cost advantage does it have compared to conventional surveying equipment? A: Although exact prices are not listed here, LRTK is designed to significantly reduce introduction and operational costs compared to expensive dedicated surveying equipment. Leveraging existing smartphones lowers initial investment, and you can start small and expand the number of units as needed. Lower cost barriers make it easier for small-scale factories and warehouses to adopt centimeter-level positioning.

Q: Can it be mounted on vehicles such as forklifts to record travel trajectories? A: Yes. LRTK is small and lightweight, so it does not interfere with operations when mounted on forklifts or carts. Combined with a smartphone, it can record and share travel routes with centimeter accuracy, allowing post-analysis of which routes were taken and where long stops occurred. This can help with safe driving instruction and improvements to logistics flows.